1. Field of the Invention
The present invention relates to a system for detecting a transmission error in digital television signals that are encoded by an inter-frame encoding system.
2. Description of the Prior Art
An inter-frame encoding/decoding system compresses the transmission band by transmitting an estimated error only, with a decoded digital television signal of a preceding frame as a predicted value. Therefore, the predicted value produced by inter-frame encoding equipment must be in agreement with the predicted value of an inter-frame decoding device. When a decoded error has occurred in the digital television signals decoded by the inter-frame decoding equipment due to a transmission error, the error remains in the decoded digital television signals unless it is corrected by some method. Therefore, the detection of a transmission error, or the detection of the fact that the predicted value of the decoding equipment is different from the predicted value of the encoding equipment, is important in the inter-frame encoding/decoding system.
A cyclic redundancy check code (CRC) system has been generally used to detect a transmission error. Even with the system for detecting a transmission error based upon the CRC system, however, as well known, sometimes the transmission error can not be detected. When a transmission error is not detected, the decoded error is left in the decoded digital television signals.